The benchmarks were done while Bifferboard was running Linux kernel 188.8.131.52 and Debian Lenny.
Total boot time: 1 minute 11 seconds (standard Debian Lenny base installation)
The boot process goes like this:
- Initial boot. Mounted root device (5 seconds wasted on waiting for the USB mass storage to be initialized). Executing INIT. [+21 seconds elapsed]
- Waiting for udev to be initialized (most of the time spent here), configuring some misc settings, no dhcp network, entering Runlevel 2. [+41 seconds elapsed]
- Started “rsyslogd”, “sshd”, “crond”. Got prompt on the serial console. [+9 seconds elapsed]
Therefore, if a very limited and custom Linux installation is used, the total boot time could be reduced almost twice.
Calculated BogoMips: 56.32
According to a quite complete BogoMips list table, this is an equivalent of Pentium@133MHz or 486DX4@100MHz.
According to another CPU benchmarks comparison table for Linux, Bifferboard falls into the category of Pentium@100Mhz.
A “dd” write to “/dev/shm” performs with a speed of 6.3 MB/s.
The MBW memory bandwidth benchmark shows the following results:
bifferboard:/tmp# dpkg -i mbw_1.1.1-1_i386.deb
bifferboard:/tmp# mbw 4 -n 20|egrep ^AVG
AVG Method: MEMCPY Elapsed: 0.15602 MiB: 4.00000 Copy:
AVG Method: DUMB Elapsed: 0.06611 MiB: 4.00000 Copy:
AVG Method: MCBLOCK Elapsed: 0.06619 MiB: 4.00000 Copy:
For comparison, my Pentium Dual-Core @ 2.50GHz with DDR2 @ 800 MHz (1.2 ns) shows a “dd” copy speed to “/dev/shm” of 271 MB/s, while the MBW test shows a maximum average speed of 7670.954 MiB/s. Bifferboard is an embedded device after all… :)
Available memory for applications
My base Debian installation with “udevd”, “dhclient3″, “rsyslogd”, “sshd”, “getty” and one tty session running shows 24908 kbytes free memory. You surely cannot put CNN.com on this little machine, but compared to the PIC16F877A which has 368 bytes (yes, bytes) total RAM memory, Bifferboard is a monster.
All tests are done on an Ext3 file-system and a very fast USB Flash 8GB A-Data Xupreme 200X.
A “dd” copy to a file completes with a write speed of 6.1 MB/s.
The Bonnie++ benchmark test shows the following results:
Version 1.03d ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
bifferboard.lo 300M 822 96 5524 61 4305 42 855 99 16576 67 143.2 12
------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 1274 94 14830 100 1965 85 1235 90 22519 100 2015 87
Therefore, the sequential write speed is about 5.5 MB/s, while the sequential read speed is about 16.5 MB/s.
It’s worth mentioning that while the write tests were running, there was a very high CPU System load (not CPU I/O waiting) which indicates that the write throughput of Bifferboard may be a bit better if the file-system is not a journaling one. However, the tests for “Memory speed” above show that writing to “/dev/shm” (a memory-based file-system) completes with a rate of 6.3 MB/s. Therefore, this is probably the limit with this configuration.
Both Netperf and Wget show a throughput of 6.5 MB/s.
The packets-per-second tests complete at a rate of 8000 packets/second.
Modern systems can handle several hundred thousand packets-per-second without an issue. However, the measured network performance of Bifferboard is more than enough for trivial network communication with the device. During the network benchmark tests, there was very high CPU System usage, but that was expected.
Encryption and SSH transfers
The maximum encryption rate for an eCryptfs mount with AES cipher and 16 bytes key length is 536 KB/s. The standard SSH Protocol 2 transfer rate using the OpenSSH server is about the same – 587.1 KB/s. If you try to transfer a file over SSH and store it on an eCryptfs mounted volume, the transfer rate is 272.2 KB/s, which is logical, as the processing power is split between the SSH transfer and the eCryptfs encryption.
You can try to tweak your OpenSSH ciphers, in order to get much better performance. The OpenSSH ciphers performance benchmark page will give you a starting point.
Bifferboard performs pretty well for its price. It’s my personal choice over the 8-bit 16F877A and the other 16-bit Microchip / ARM microcontrollers, when a project does not require very fast I/O.